Approach to altered mental status: Clinical sciences

Altered mental status refers to the abnormal change in consciousness, cognition, behavior, or mood, which can range from mild confusion to coma. It can occur suddenly, like following acute intoxication, or gradually, as in hepatic encephalopathy. Altered mental status can arise from various causes, including abnormal glucose levels, toxins and medications, central nervous system conditions, infections, and metabolic disorders.

If your patient presents with altered mental status, perform an ABCDE assessment and start acute management. Stabilize the patient’s airway, breathing, and circulation. Next, assess their level of consciousness by checking the Glasgow Coma Scale or GCS, which measures eye-opening, verbal, and motor response to stimuli on a scale from 3 to 15. A GCS score of 3 represents a comatose state, while a score of 15 represents a normal level of consciousness. Moreover, individuals with a GCS of 8 or less might require intubation. After that, obtain IV access and check a fingerstick glucose. If it is low, give IV glucose. If you suspect opioid intoxication, administer naloxone. Lastly, don’t forget to start continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry.

Once you stabilize your patient, obtain a focused history and physical examination. Since these patients are often unable to provide a history, you may need to gather information from family members, caretakers, or witnesses. History usually reveals a change in the patient’s level of consciousness, behavior, or mood, which can be persistent or fluctuate in severity with time. Additionally, the physical exam reveals a decreased level of consciousness, as well as confusion and memory loss.

As you are dealing with altered mental status, your next step is to assess the underlying cause. Start by obtaining serum glucose levels. If glucose levels are above 250 mg/dL, consider hyperglycemic hyperosmolar syndrome or HHS or diabetic ketoacidosis or DKA, and order labs including arterial blood gas, known as ABG, or venous blood gas analysis, also known as VBG; serum osmolality; CMP; and serum and urine ketones like beta-hydroxybutyrate.

If labs reveal glucose levels above 600 mg/dL; pH above 7.3; bicarbonate levels greater than 18 with variable anion gap; serum osmolality above 320 mOsm/kg; with minimal to no serum and urine ketones, you are dealing with hyperosmolar hyperglycemic syndrome or HHS.

Alternatively, if labs reveal glucose levels above 250 mg/dL; pH less than 7.3; bicarbonate levels less than 15; increased anion gap, variable serum osmolality; and high serum and urine ketone levels, your patient has diabetic ketoacidosis or DKA. Going back a step, if the serum glucose is below 55 to 70 mg/dL, the cause of altered mental status is hypoglycemia.

Let’s switch gears and talk about normal glucose levels. First, you should rule out hypoxia or hypercapnia. If your patient presents with shortness of breath, and their physical exam reveals an abnormal respiratory rate, abnormal lung sounds, and possibly cyanosis, consider hypoxia or hypercapnia and obtain ABG. If the ABG reveals decreased partial pressure of oxygen, your patient has hypoxia, but if it shows an elevated partial pressure of carbon dioxide, that’s hypercapnia.

Next, you should look for toxin- and medication-induced altered mental status. Some individuals might have a history of recent substance use, which may include CNS stimulants like amphetamines or depressants like opioids. Physical exam findings can vary based on the substance involved. For example, CNS stimulants might result in diaphoresis, an increased respiratory rate, and dilated pupils. On the other hand, CNS depressants are typically associated with a decreased respiratory rate, and constricted pupils.

In this case, consider intoxication, and order a urine toxicology screen and serum alcohol level. If either comes back positive diagnose intoxication as the cause of the altered mental status.

Next up is withdrawal syndrome. These patients present with a history of a recent reduction or cessation of alcohol or substance use. The physical exam shows agitation, increased heart rate, and blood pressure; or depression and fatigue if they are experiencing withdrawal from stimulants.

With these findings, consider withdrawal syndrome, and again, order a urine toxicology screen and serum alcohol levels. If the results are negative, the substance has been metabolized and eliminated from the body, so the cause of altered mental status is probably withdrawal syndrome.

Here’s a clinical pearl! A positive serum alcohol level does not necessarily rule out alcohol withdrawal. Sometimes, individuals with prolonged, heavy alcohol use can experience withdrawal even when they still have detectable serum alcohol levels. They are at high risk of severe withdrawal, which can be life-threatening.

Moving on to medication adverse effects. History reveals the use of medications with known CNS side effects, such as antiepileptics, antipsychotics, and sedatives. If the suspected medication was recently started, your patient’s altered mental status is probably due to that medication’s adverse effects.